基本 Apache 模块中的链接器错误

Question

我正在尝试为 Apache HTTPD 2.4 编写 "hello world" 模块。我在构建模块时收到一些链接器错误，许多 Google 搜索都没有找到解决方案。

我的问题是：

如何解决 ap_hook_handler 链接器错误？我搜索了 Apache Portable Runtime 源和 headers 但没有找到它。
为什么有对 main 的未定义引用？我认为共享 objects 没有 main() 入口点。

源代码：

// Dependancies: apr-devel apr-util-devel

#include <httpd.h>
#include <http_config.h>
#include <apr_hooks.h>

static int test_handler(request_rec* request)
{
        return OK;
}

static void register_hooks(apr_pool_t *pool)
{
        ap_hook_handler(test_handler, NULL, NULL, APR_HOOK_LAST);
}

module AP_MODULE_DECLARE_DATA test_module =
{
        STANDARD20_MODULE_STUFF,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
        register_hooks
};

构建命令：

apxs -lapr-1 -laprutil-1 -c test.c -o mod_test.so

错误：

apxs -lapr-1 -laprutil-1 -c test.c -o mod_test.so
/usr/lib64/apr-1/build/libtool --silent --mode=compile gcc -prefer-pic -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -Wformat-security -fno-strict-aliasing  -DLINUX=2 -D_REENTRANT -D_GNU_SOURCE -pthread -I/usr/include/httpd  -I/usr/include/apr-1   -I/usr/include/apr-1   -c -o test.lo test.c && touch test.slo
/usr/lib64/apr-1/build/libtool --silent --mode=link gcc -o test.la  -lapr-1 -laprutil-1 -rpath /usr/lib64/httpd/modules -module -avoid-version    test.lo -o mod_test.so
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
.libs/test.o: In function `register_hooks':
/root/test/test.c:14: undefined reference to `ap_hook_handler'
collect2: ld returned 1 exit status
apxs:Error: Command failed with rc=65536

Answer 1

顺序很重要，文件名必须放在最后：

apxs -c -o mod_test.so test.c

自动安装：

apxs -i -c -o mod_test.so -c test.c

这应该有效

Answer 2

正如ctx所说，参数的顺序真的很重要。我使用以下格式的 APXS：

$APACHE/bin/apxs -c -a -i mod_test.c

什么编译、添加和安装测试模块。它产生这个输出：

/usr/local/apr/build-1/libtool --silent --mode=compile gcc -prefer-pic   -DLINUX -D_REENTRANT -D_GNU_SOURCE -g -O2 -pthread -I$APACHE_HOME/include  -I/usr/local/apr/include/apr-1   -I/usr/local/apr/include/apr-1   -c -o mod_test.lo mod_test.c && touch mod_test.slo
/usr/local/apr/build-1/libtool --silent --mode=link gcc    -o mod_test.la  -rpath $APACHE_HOME/modules -module -avoid-version mod_test.lo
ar: `u' modifier ignored since `D' is the default (see `U')
$APACHE_HOME/build/instdso.sh SH_LIBTOOL='/usr/local/apr/build-1/libtool' mod_test.la $APACHE_HOME/modules
/usr/local/apr/build-1/libtool --mode=install install mod_test.la $APACHE_HOME/modules/
libtool: install: install .libs/mod_test.so $APACHE_HOME/modules/mod_test.so
libtool: install: install .libs/mod_test.lai $APACHE_HOME/modules/mod_test.la
libtool: install: install .libs/mod_test.a $APACHE_HOME/modules/mod_test.a
libtool: install: chmod 644 $APACHE_HOME/modules/mod_test.a
libtool: install: ranlib $APACHE_HOME/modules/mod_test.a
libtool: finish: 
----------------------------------------------------------------------
Libraries have been installed in:
   $APACHE_HOME/modules

If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the `-LLIBDIR'
flag during linking and do at least one of the following:
   - add LIBDIR to the `LD_LIBRARY_PATH' environment variable
     during execution
   - add LIBDIR to the `LD_RUN_PATH' environment variable
     during linking
   - use the `-Wl,-rpath -Wl,LIBDIR' linker flag
   - have your system administrator add LIBDIR to `/etc/ld.so.conf'

See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.
----------------------------------------------------------------------
chmod 755 $APACHE_HOME/modules/mod_test.so
[activating module `test' in $APACHE_HOME/conf/httpd.conf]

通过提供 -o 选项，您可以摆脱 undefined reference to main 错误消息。

基本 Apache 模块中的链接器错误

Linker errors in a basic Apache module

c

apache

apr